Xinggui Shen | Louisiana State University Health Sciences Center - Shreveport (original) (raw)
Papers by Xinggui Shen
Nature Reviews Cardiology
Hydrogen sulfide (H 2 S) has emerged as a gaseous signalling molecule with crucial implications f... more Hydrogen sulfide (H 2 S) has emerged as a gaseous signalling molecule with crucial implications for cardiovascular health. H 2 S is involved in many biological functions, including interactions with nitric oxide, activation of molecular signalling cascades, post-translational modifications and redox regulation. Various preclinical and clinical studies have shown that H 2 S and its synthesizing enzymes-cystathionine γ-lyase, cystathionine β-synthase and 3-mercaptosulfotransferase-can protect against cardiovascular pathologies, including arrhythmias, atherosclerosis, heart failure, myocardial infarction and ischaemia-reperfusion injury. The bioavailability of H 2 S and its metabolites, such as hydropersulfides and polysulfides, is substantially reduced in cardiovascular disease and has been associated with single-nucleotide polymorphisms in H 2 S synthesis enzymes. In this Review, we highlight the role of H 2 S, its synthesizing enzymes and metabolites, their roles in the cardiovascular system, and their involvement in cardiovascular disease and associated pathologies. We also discuss the latest clinical findings from the field and outline areas for future study.
Chemical Research in Chinese Universities, 2006
ABSTRACT Phosphatase of Regenerating Liver-3 (PRL-3) is a newly identified colorectal cancer meta... more ABSTRACT Phosphatase of Regenerating Liver-3 (PRL-3) is a newly identified colorectal cancer metastasis-related protein, which is a 22 kDa non-classical protein tyrosine phosphatase with a C-terminal prenylation motif. In this study, the inhibition kinetics of protein tyrosine phosphatases (PTPs) by a fluorescent substrate, 6,8-difluoro-4-methylumbelliferyl phosphate (DiFMUP) was evaluated. PRL-3 exhibits classical Michaelis-Menten kinetics with a vmax value of 11.3 μmol · L−1 · min−1. Analysis of PRL-3 by a Michaelis-Menten plot and a double-reciprocal plot indicated that the inhibitor magnolol can cause Km to increase, but does not alter the vmax value, which suggests the competitive inhibition of PRL-3. At the same time, it was found that DiFMUP is a more sensitive substrate for PRL-3 than para-nitro-phenyl phosphate (pNPP) that is more frequently used at present. Furthermore, the method of screening for PTPs by the use of DiFMUP was developed, which studied the acceptance of DiFMUP by other PTPs.
Chemical Research in Chinese Universities, 2006
... CHINESE U. 2006, 22( 1) , 68-72 PRLs Promote Spreading, Adhesion, and Proliferation of Human ... more ... CHINESE U. 2006, 22( 1) , 68-72 PRLs Promote Spreading, Adhesion, and Proliferation of Human SW480 and SW620 Cells* LI Zhao-fa' , XU Xue-song2, SHEN Xing-gui' , LI Qing-shan' , ZHAO Zhi-zhuang' , FU Xue-qi ... Time /h Fig.4 References Boyd D. , Cancer Metastasis Reu. ...
Molecular carcinogenesis, Jan 16, 2015
Withaferin A (WA), a natural product derived from Withania somnifera, has been used in traditiona... more Withaferin A (WA), a natural product derived from Withania somnifera, has been used in traditional oriental medicines to treat neurological disorders. Recent studies have demonstrated that this compound may have a potential for cancer treatment and a clinical trial has been launched to test WA in treating melanoma. Herein, WA's chemopreventive potential was tested in a chemically-induced skin carcinogenesis mouse model. Pathological examinations revealed that WA significantly suppressed skin tumor formation. Morphological observations of the skin tissues suggest that WA suppressed cell proliferation rather than inducing apoptosis during skin carcinogenesis. Antibody Micro array analysis demonstrated that WA blocked carcinogen-induced up-regulation of acetyl-CoA carboxylase 1 (ACC1), which was further confirmed in a skin cell transformation model. Overexpression of ACC1 promoted whereas knockdown of ACC1 suppressed anchorage-independent growth and oncogene activation of transform...
Cardiovascular research, Jan 20, 2015
Hydrogen sulfide (H2S) is a vasoactive gasotransmitter that is endogenously produced in the vascu... more Hydrogen sulfide (H2S) is a vasoactive gasotransmitter that is endogenously produced in the vasculature by the enzyme cystathionine γ-lyase (CSE). However, the importance of CSE activity and local H2S generation for ischemic vascular remodeling remains completely unknown. In this study, we examine the hypothesis that CSE critically regulates ischemic vascular remodeling involving H2S dependent mononuclear cell regulation of arteriogenesis. Arteriogenesis including mature vessel density, collateral formation; blood flow and SPY angiographic blush rate were determined in WT and CSE knockout mice at different time points following femoral artery ligation (FAL). The role of endogenous H2S in regulation of IL-16 expression and subsequent recruitment of monocytes, and expression of VEGF and bFGF in ischemic tissues, were determined along with EPC (CD34/Flk1) formation and function. FAL of wild type mice significantly increased CSE activity, expression and endogenous H2S generation in isch...
Journal of the American Heart Association, 2012
Hydrogen sulfide (H(2)S) therapy is recognized as a modulator of vascular function during tissue ... more Hydrogen sulfide (H(2)S) therapy is recognized as a modulator of vascular function during tissue ischemia with the notion of potential interactions of nitric oxide (NO) metabolism. However, little is known about specific biochemical mechanisms or the importance of H(2)S activation of NO metabolism during ischemic tissue vascular remodeling. The goal of this study was to determine the effect of H(2)S on NO metabolism during chronic tissue ischemia and subsequent effects on ischemic vascular remodeling responses. The unilateral, permanent femoral artery ligation model of hind-limb ischemia was performed in C57BL/6J wild-type and endothelial NO synthase-knockout mice to evaluate exogenous H(2)S effects on NO bioavailability and ischemic revascularization. We found that H(2)S selectively restored chronic ischemic tissue function and viability by enhancing NO production involving both endothelial NO synthase and nitrite reduction mechanisms. Importantly, H(2)S increased ischemic tissue x...
Journal of the American Heart Association, 2013
Background--Hydrogen sulfide (H 2 S) has been implicated in regulating cardiovascular pathophysio... more Background--Hydrogen sulfide (H 2 S) has been implicated in regulating cardiovascular pathophysiology in experimental models. However, there is a paucity of information regarding the levels of H 2 S in health and cardiovascular disease. In this study we examine the levels of H 2 S in patients with cardiovascular disease as well as bioavailability of nitric oxide and inflammatory indicators.
Free Radical Biology and Medicine, 2013
Cancer prevention research (Philadelphia, Pa.), Jan 17, 2015
Mitochondrial uncoupling (uncouples electron transport from ATP production) has recently been pro... more Mitochondrial uncoupling (uncouples electron transport from ATP production) has recently been proposed as a novel survival mechanism for cancer cells, and reduction in free radical generation is the accepted mechanism of action. However, there is no direct evidence supporting that uncoupling proteins promote carcinogenesis. Herein, we examined whether mitochondrial uncoupling affects mouse skin carcinogenesis using uncoupling protein 2 (UCP2) homozygous knockout and wild-type mice. The results indicate that knockout of UCP2 significantly reduced the formation of both benign (papilloma) and malignant (squamous cell carcinoma) tumors. UCP2 knockout did not cause increases in apoptosis during skin carcinogenesis. The rates of oxygen consumption were only decreased in the carcinogen-treated UCP2 knockout mice whereas glycolysis was only increased in the carcinogen-treated wild-type mice. Finally, the levels of metabolites pyruvate, malate and succinate showed different trends after carc...
Free Radical Biology and Medicine, 2014
During winter hibernation, brown bears (Ursus arctos) lie in dens for half a year without eating ... more During winter hibernation, brown bears (Ursus arctos) lie in dens for half a year without eating while their basal metabolism is largely suppressed. To understand the underlying mechanisms of metabolic depression in hibernation, we measured type and content of blood metabolites of two ubiquitous inhibitors of mitochondrial respiration, hydrogen sulfide (H 2 S) and nitric oxide (NO), in winterhibernating and summer-active free-ranging Scandinavian brown bears. We found that levels of sulfide metabolites were overall similar in summer-active and hibernating bears but their composition in the plasma differed significantly, with a decrease in bound sulfane sulfur in hibernation. High levels of unbound free sulfide correlated with high levels of cysteine (Cys) and with low levels of bound sulfane sulfur, indicating that during hibernation H 2 S, in addition to being formed enzymatically from the substrate Cys, may also be regenerated from its oxidation products, including thiosulfate and polysulfides. In the absence of any dietary intake, this shift in the mode of H 2 S synthesis would help preserve free Cys for synthesis of glutathione (GSH), a major antioxidant found at high levels in the red blood cells of hibernating bears. In contrast, circulating nitrite and erythrocytic S-nitrosation of glyceraldehyde-3-phosphate dehydrogenase, taken as markers of NO metabolism, did not change appreciably. Our findings reveal that remodeling of H 2 S metabolism and enhanced intracellular GSH levels are hallmarks of the aerobic metabolic suppression of hibernating bears.
Nitric Oxide, 2014
Accurate measurement of hydrogen sulfide bioavailability remains a technical challenge due to num... more Accurate measurement of hydrogen sulfide bioavailability remains a technical challenge due to numerous issues involving sample processing, detection methods used, and actual biochemical products measured. Our group and others have reported that reverse phase HPLC detection of sulfide dibimane (SDB) product from the reaction of H2S/HS(-) with monobromobimane allows for analytical detection of hydrogen sulfide bioavailability in free and other biochemical forms. However, it remains unclear whether possible interfering contaminants may contribute to HPLC SDB peak readings that may result in inaccurate measurements of bioavailable sulfide. In this study, we critically compared hydrogen sulfide dependent SDB detection using reverse phase HPLC (RP-HPLC) versus quantitative SRM electrospray ionization mass spectrometry (ESI/MS) to obtain greater clarity into the validity of the reverse phase HPLC method for analytical measurement of hydrogen sulfide. Using an LCQ-Deca ion-trap mass spectrometer, SDB was identified by ESI/MS positive ion mode, and quantified by selected reaction monitoring (SRM) using hydrocortisone as an internal standard. Collision induced dissociation (CID) parameters were optimized at MS2 level for SDB and hydrocortisone. ESI/MS detection of SDB standard was found to be a log order more sensitive than RP-HPLC with a lower limit of 0.25 nM. Direct comparison of tissue and plasma SDB levels using RP-HPLC and ESI/MS methods revealed comparable sulfide levels in plasma, aorta, heart, lung and brain. Together, these data confirm the use of SDB as valid indicator of H2S bioavailability and highlights differences between analytical detection methods.
Methods in Enzymology, 2015
The gasotransmitter hydrogen sulfide (H2S) is known as an important regulator in several physiolo... more The gasotransmitter hydrogen sulfide (H2S) is known as an important regulator in several physiological and pathological responses. Among the challenges facing the field is the accurate and reliable measurement of hydrogen sulfide bioavailability. We have reported an approach to discretely measure sulfide and sulfide pools using the monobromobimane (MBB) method coupled with reversed phase high-performance liquid chromatography (RP-HPLC). The method involves the derivatization of sulfide with excess MBB under precise reaction conditions at room temperature to form sulfide dibimane (SDB). The resultant fluorescent SDB is analyzed by RP-HPLC using fluorescence detection with the limit of detection for SDB (2nM). Care must be taken to avoid conditions that may confound H2S measurement with this method. Overall, RP-HPLC with fluorescence detection of SDB is a useful and powerful tool to measure biological sulfide levels.
Methods in Enzymology, 2015
Nitric oxide (NO) and hydrogen sulfide (H2S) are two major gaseous signaling molecules that regul... more Nitric oxide (NO) and hydrogen sulfide (H2S) are two major gaseous signaling molecules that regulate diverse physiological functions. Recent publications indicate the regulatory role of H2S on NO metabolism. In this chapter, we discuss the latest findings on H2S-NO interactions through formation of novel chemical derivatives and experimental approaches to study these adducts. This chapter also addresses potential H2S interference on various NO detection techniques, along with precautions for analyzing biological samples from various sources. This information will facilitate critical evaluation and clearer insight into H2S regulation of NO signaling and its influence on various physiological functions.
Nitric Oxide, 2012
ABSTRACT Introduction Hydrogen sulfide is a gaseous signaling molecule which is produced in vivo ... more ABSTRACT Introduction Hydrogen sulfide is a gaseous signaling molecule which is produced in vivo by three enzymes such as cystathionine γ-lyase (CSE), cystathionine β- synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (MST) from L-cysteine.CSE is the prime enzyme among others for sulfide production in vascular tissues of our body. Hydrogen sulfide is reported to have vasodilatory, anti–inflammatory, anti-oxidant, cytoprotective and pro-angiogenic effects. Sulfide production is decreased in diabetic condition. However, the molecular mechanisms of sulfide-mediated protection during chronic tissue ischemia in diabetic condition are completely unknown. Objective To determine molecular mechanisms involved in hydrogen sulfide mediated cytoprotection during chronic tissue ischemia in diabetic condition. Methods Hind limb ischemia was induced in 10 week old wild type, 42 week old Db/Db diabetic or 10–12 week old CSE knock out (CSEKO, n = 8, each group). PBS, 0.1, 0.5 and 1 mg/kg sodium sulfide (Na2S) was administered twice daily by retro-orbital injection. Hind limb perfusion was measured using a laser Doppler perfusion probe. SPY imaging was performed to determine the collateral formation in different time points. Capillary myofiber ratio was determined by NOVA Red staining with CD31 antibody. Mature vessel density and proliferation index were determined by the ratio of smooth muscle actin (SMA) to DAPI and Ki67 to DAPI positive areas respectively. TUNEL assay was measured to investigate the apoptosis. Nitric oxide (NO) was measured by NO analyzer (NOA). CPTIO (1 mg/kg/day) was injected intra-peritoneally to determine the effect of NO in sulfide induced ischemic angiogenesis. VEGF aptamer (50 mg/kg/day) was injected locally to the ischemic muscle to determine the role of VEGF in sulfide induced ischemic angiogenesis. Lastly, VEGF expression was determined by ELISA. Result Blood perfusion, blush rate by SPY imaging, angiogenic index, proliferation index and mature vessel density were significantly decreased in CSEKO mice compared WT mice indicating the role of sulfide on ischemic angiogeneis and arteriogenesis. Na2S dose dependently increases the angiogenesis index, proliferation index, mature vessel density and restores the blood flow in WT mice. Hydrogen sulfide also rescues the impaired blood flow in CSEKO mice by increasing angiogenic index, proliferation index and mature vessel density. Blood tissue perfusion, proliferation index, capillary to myofiber ratio and VEGF expression were all significantly increased and conversely, apoptosis was prevented in ischemic hind limbs of aged diabetic mice treated with Na2S compared to PBS control. There was no effect of sulfide on blood glucose, body weight and lipid profiles of diabetic mice.Total NO production was increased in sulfide treated group compared to PBS which was inhibited by CPTIO treatment. Lastly, VEGF164 aptamer blocked sulfide induced augmentation of blood flow and reduced the expression of VEGF164 in WT and diabetic mice hind limb ischemia indicating VEGF164 as the sulfide induced angiogenic stimulator. Conclusion Sodium sulfide therapy restores tissue perfusion of critical limb ischemia by increasing production of NO, increasing expression of VEGF and preventing apoptosis in diabetic mouse chronic hind limb ischemia which may be beneficial for the diabetic patient with peripheral vascular disease.
Nitric Oxide, 2013
Hydrogen sulfide (H 2 S) is the most recent endogenous gasotransmitter that has been reported to ... more Hydrogen sulfide (H 2 S) is the most recent endogenous gasotransmitter that has been reported to serve many physiological and pathological functions in different tissues. Studies over the past decade have revealed that H 2 S can be synthesized through numerous pathways and its bioavailability regulated through its conversion into different biochemical forms. H 2 S exerts its biological effects in various manners including redox regulation of protein and small molecular weight thiols, polysulfides, thiosulfate/ sulfite, iron-sulfur cluster proteins, and anti-oxidant properties that affect multiple cellular and molecular responses. However, precise measurement of H 2 S bioavailability and its associated biochemical and pathophysiological roles remains less well understood. In this review, we discuss recent understanding of H 2 S chemical biology, its relationship to tissue pathophysiological responses and possible therapeutic uses.
Nitric Oxide, 2013
ABSTRACT Although animal studies concerning cytokines or stem cell therapies have shown hope for ... more ABSTRACT Although animal studies concerning cytokines or stem cell therapies have shown hope for arteriogenesis, clinical results have been disappointing due to multi-factoral causes. Monocyte signaling is a dominant and important mediator of arteriogenesis activity and monocyte-signaling pathways can be severely impaired during various cardiovascular disorders. Hydrogen sulfide (H2S) is produced by cystathionine-γ lyase (CSE), and a potential gaseous molecule that has many positive cytoprotective effects including regulation of monocyte functions. However, a molecular mechanism of CSE/H2S regulation of arteriogenesis during ischemia is not established. Therefore, we hypothesized that CSE/H2S modulates arterial collateral formation in mouse hind limb ischemia via IL-16/bFGF dependent pathway. Unilateral permanent hind limb ischemia was induced in wild type (WT) and CSE(-/-) mice. Mice were then randomly assigned into four groups (8 mice, each group); WT PBS, WT DATS (a hydrogen sulfide donor, 200μg/kg, twice daily, IV until day 21), CSE(-) PBS, CSE(-/-) DATS. CSE activity and H2S levels in monocytes and tissues were determined in ischemic conditions and with inflammatory agents and studied both in vitro and in vivo. Tissue perfusion was determined using laser Doppler perfusion imaging system and the number and diameter of arterial collaterals measured using SPY angiography. Mature vessel density and monocyte recruitment was investigated by α-SMA/CD31/DAPI and MAC-2/DAPI positive staining. ELISA was used to measure IL-16 and bFGF levels. CSE activity and free H2S levels were increased during ischemia and TNF- α stimulation in cultured monocytes. CSE activity and H2S levels were also elevated in bone marrow derived and circulating monocytes, and tissues after ischemia induction in WT mice but not from CSE(-/-) mice. Blood perfusion, blush rate, number and diameter of collaterals, and mature vessel density were decreased in CSE(-/-) mice compared to WT mice that was rescued by DATS therapy. IL-16 levels were reduced in ischemic tissue of CSE(-/-) mice compared to WT mice. IL-16 levels were restored by DATS treatment in ischemic tissue of CSE(-) mice. Monocyte recruitment was significantly reduced in ischemic tissues of CSE(-/-) mice that were rescued by DATS treatment. Lastly bFGF levels were less in ischemic tissue of CSE(-/-) mice compared to WT mice and that were restored by DATS therapy. CSE/H2S regulates arteriogenesis via IL-16 mediated monocyte recruitment and up-regulation of bFGF levels in ischemic tissue of CSE(-/-) mice. These findings reveal a novel role of monocyte dependent CSE/H2S in regulating arteriogenesis activity.
Nature Reviews Cardiology
Hydrogen sulfide (H 2 S) has emerged as a gaseous signalling molecule with crucial implications f... more Hydrogen sulfide (H 2 S) has emerged as a gaseous signalling molecule with crucial implications for cardiovascular health. H 2 S is involved in many biological functions, including interactions with nitric oxide, activation of molecular signalling cascades, post-translational modifications and redox regulation. Various preclinical and clinical studies have shown that H 2 S and its synthesizing enzymes-cystathionine γ-lyase, cystathionine β-synthase and 3-mercaptosulfotransferase-can protect against cardiovascular pathologies, including arrhythmias, atherosclerosis, heart failure, myocardial infarction and ischaemia-reperfusion injury. The bioavailability of H 2 S and its metabolites, such as hydropersulfides and polysulfides, is substantially reduced in cardiovascular disease and has been associated with single-nucleotide polymorphisms in H 2 S synthesis enzymes. In this Review, we highlight the role of H 2 S, its synthesizing enzymes and metabolites, their roles in the cardiovascular system, and their involvement in cardiovascular disease and associated pathologies. We also discuss the latest clinical findings from the field and outline areas for future study.
Chemical Research in Chinese Universities, 2006
ABSTRACT Phosphatase of Regenerating Liver-3 (PRL-3) is a newly identified colorectal cancer meta... more ABSTRACT Phosphatase of Regenerating Liver-3 (PRL-3) is a newly identified colorectal cancer metastasis-related protein, which is a 22 kDa non-classical protein tyrosine phosphatase with a C-terminal prenylation motif. In this study, the inhibition kinetics of protein tyrosine phosphatases (PTPs) by a fluorescent substrate, 6,8-difluoro-4-methylumbelliferyl phosphate (DiFMUP) was evaluated. PRL-3 exhibits classical Michaelis-Menten kinetics with a vmax value of 11.3 μmol · L−1 · min−1. Analysis of PRL-3 by a Michaelis-Menten plot and a double-reciprocal plot indicated that the inhibitor magnolol can cause Km to increase, but does not alter the vmax value, which suggests the competitive inhibition of PRL-3. At the same time, it was found that DiFMUP is a more sensitive substrate for PRL-3 than para-nitro-phenyl phosphate (pNPP) that is more frequently used at present. Furthermore, the method of screening for PTPs by the use of DiFMUP was developed, which studied the acceptance of DiFMUP by other PTPs.
Chemical Research in Chinese Universities, 2006
... CHINESE U. 2006, 22( 1) , 68-72 PRLs Promote Spreading, Adhesion, and Proliferation of Human ... more ... CHINESE U. 2006, 22( 1) , 68-72 PRLs Promote Spreading, Adhesion, and Proliferation of Human SW480 and SW620 Cells* LI Zhao-fa' , XU Xue-song2, SHEN Xing-gui' , LI Qing-shan' , ZHAO Zhi-zhuang' , FU Xue-qi ... Time /h Fig.4 References Boyd D. , Cancer Metastasis Reu. ...
Molecular carcinogenesis, Jan 16, 2015
Withaferin A (WA), a natural product derived from Withania somnifera, has been used in traditiona... more Withaferin A (WA), a natural product derived from Withania somnifera, has been used in traditional oriental medicines to treat neurological disorders. Recent studies have demonstrated that this compound may have a potential for cancer treatment and a clinical trial has been launched to test WA in treating melanoma. Herein, WA's chemopreventive potential was tested in a chemically-induced skin carcinogenesis mouse model. Pathological examinations revealed that WA significantly suppressed skin tumor formation. Morphological observations of the skin tissues suggest that WA suppressed cell proliferation rather than inducing apoptosis during skin carcinogenesis. Antibody Micro array analysis demonstrated that WA blocked carcinogen-induced up-regulation of acetyl-CoA carboxylase 1 (ACC1), which was further confirmed in a skin cell transformation model. Overexpression of ACC1 promoted whereas knockdown of ACC1 suppressed anchorage-independent growth and oncogene activation of transform...
Cardiovascular research, Jan 20, 2015
Hydrogen sulfide (H2S) is a vasoactive gasotransmitter that is endogenously produced in the vascu... more Hydrogen sulfide (H2S) is a vasoactive gasotransmitter that is endogenously produced in the vasculature by the enzyme cystathionine γ-lyase (CSE). However, the importance of CSE activity and local H2S generation for ischemic vascular remodeling remains completely unknown. In this study, we examine the hypothesis that CSE critically regulates ischemic vascular remodeling involving H2S dependent mononuclear cell regulation of arteriogenesis. Arteriogenesis including mature vessel density, collateral formation; blood flow and SPY angiographic blush rate were determined in WT and CSE knockout mice at different time points following femoral artery ligation (FAL). The role of endogenous H2S in regulation of IL-16 expression and subsequent recruitment of monocytes, and expression of VEGF and bFGF in ischemic tissues, were determined along with EPC (CD34/Flk1) formation and function. FAL of wild type mice significantly increased CSE activity, expression and endogenous H2S generation in isch...
Journal of the American Heart Association, 2012
Hydrogen sulfide (H(2)S) therapy is recognized as a modulator of vascular function during tissue ... more Hydrogen sulfide (H(2)S) therapy is recognized as a modulator of vascular function during tissue ischemia with the notion of potential interactions of nitric oxide (NO) metabolism. However, little is known about specific biochemical mechanisms or the importance of H(2)S activation of NO metabolism during ischemic tissue vascular remodeling. The goal of this study was to determine the effect of H(2)S on NO metabolism during chronic tissue ischemia and subsequent effects on ischemic vascular remodeling responses. The unilateral, permanent femoral artery ligation model of hind-limb ischemia was performed in C57BL/6J wild-type and endothelial NO synthase-knockout mice to evaluate exogenous H(2)S effects on NO bioavailability and ischemic revascularization. We found that H(2)S selectively restored chronic ischemic tissue function and viability by enhancing NO production involving both endothelial NO synthase and nitrite reduction mechanisms. Importantly, H(2)S increased ischemic tissue x...
Journal of the American Heart Association, 2013
Background--Hydrogen sulfide (H 2 S) has been implicated in regulating cardiovascular pathophysio... more Background--Hydrogen sulfide (H 2 S) has been implicated in regulating cardiovascular pathophysiology in experimental models. However, there is a paucity of information regarding the levels of H 2 S in health and cardiovascular disease. In this study we examine the levels of H 2 S in patients with cardiovascular disease as well as bioavailability of nitric oxide and inflammatory indicators.
Free Radical Biology and Medicine, 2013
Cancer prevention research (Philadelphia, Pa.), Jan 17, 2015
Mitochondrial uncoupling (uncouples electron transport from ATP production) has recently been pro... more Mitochondrial uncoupling (uncouples electron transport from ATP production) has recently been proposed as a novel survival mechanism for cancer cells, and reduction in free radical generation is the accepted mechanism of action. However, there is no direct evidence supporting that uncoupling proteins promote carcinogenesis. Herein, we examined whether mitochondrial uncoupling affects mouse skin carcinogenesis using uncoupling protein 2 (UCP2) homozygous knockout and wild-type mice. The results indicate that knockout of UCP2 significantly reduced the formation of both benign (papilloma) and malignant (squamous cell carcinoma) tumors. UCP2 knockout did not cause increases in apoptosis during skin carcinogenesis. The rates of oxygen consumption were only decreased in the carcinogen-treated UCP2 knockout mice whereas glycolysis was only increased in the carcinogen-treated wild-type mice. Finally, the levels of metabolites pyruvate, malate and succinate showed different trends after carc...
Free Radical Biology and Medicine, 2014
During winter hibernation, brown bears (Ursus arctos) lie in dens for half a year without eating ... more During winter hibernation, brown bears (Ursus arctos) lie in dens for half a year without eating while their basal metabolism is largely suppressed. To understand the underlying mechanisms of metabolic depression in hibernation, we measured type and content of blood metabolites of two ubiquitous inhibitors of mitochondrial respiration, hydrogen sulfide (H 2 S) and nitric oxide (NO), in winterhibernating and summer-active free-ranging Scandinavian brown bears. We found that levels of sulfide metabolites were overall similar in summer-active and hibernating bears but their composition in the plasma differed significantly, with a decrease in bound sulfane sulfur in hibernation. High levels of unbound free sulfide correlated with high levels of cysteine (Cys) and with low levels of bound sulfane sulfur, indicating that during hibernation H 2 S, in addition to being formed enzymatically from the substrate Cys, may also be regenerated from its oxidation products, including thiosulfate and polysulfides. In the absence of any dietary intake, this shift in the mode of H 2 S synthesis would help preserve free Cys for synthesis of glutathione (GSH), a major antioxidant found at high levels in the red blood cells of hibernating bears. In contrast, circulating nitrite and erythrocytic S-nitrosation of glyceraldehyde-3-phosphate dehydrogenase, taken as markers of NO metabolism, did not change appreciably. Our findings reveal that remodeling of H 2 S metabolism and enhanced intracellular GSH levels are hallmarks of the aerobic metabolic suppression of hibernating bears.
Nitric Oxide, 2014
Accurate measurement of hydrogen sulfide bioavailability remains a technical challenge due to num... more Accurate measurement of hydrogen sulfide bioavailability remains a technical challenge due to numerous issues involving sample processing, detection methods used, and actual biochemical products measured. Our group and others have reported that reverse phase HPLC detection of sulfide dibimane (SDB) product from the reaction of H2S/HS(-) with monobromobimane allows for analytical detection of hydrogen sulfide bioavailability in free and other biochemical forms. However, it remains unclear whether possible interfering contaminants may contribute to HPLC SDB peak readings that may result in inaccurate measurements of bioavailable sulfide. In this study, we critically compared hydrogen sulfide dependent SDB detection using reverse phase HPLC (RP-HPLC) versus quantitative SRM electrospray ionization mass spectrometry (ESI/MS) to obtain greater clarity into the validity of the reverse phase HPLC method for analytical measurement of hydrogen sulfide. Using an LCQ-Deca ion-trap mass spectrometer, SDB was identified by ESI/MS positive ion mode, and quantified by selected reaction monitoring (SRM) using hydrocortisone as an internal standard. Collision induced dissociation (CID) parameters were optimized at MS2 level for SDB and hydrocortisone. ESI/MS detection of SDB standard was found to be a log order more sensitive than RP-HPLC with a lower limit of 0.25 nM. Direct comparison of tissue and plasma SDB levels using RP-HPLC and ESI/MS methods revealed comparable sulfide levels in plasma, aorta, heart, lung and brain. Together, these data confirm the use of SDB as valid indicator of H2S bioavailability and highlights differences between analytical detection methods.
Methods in Enzymology, 2015
The gasotransmitter hydrogen sulfide (H2S) is known as an important regulator in several physiolo... more The gasotransmitter hydrogen sulfide (H2S) is known as an important regulator in several physiological and pathological responses. Among the challenges facing the field is the accurate and reliable measurement of hydrogen sulfide bioavailability. We have reported an approach to discretely measure sulfide and sulfide pools using the monobromobimane (MBB) method coupled with reversed phase high-performance liquid chromatography (RP-HPLC). The method involves the derivatization of sulfide with excess MBB under precise reaction conditions at room temperature to form sulfide dibimane (SDB). The resultant fluorescent SDB is analyzed by RP-HPLC using fluorescence detection with the limit of detection for SDB (2nM). Care must be taken to avoid conditions that may confound H2S measurement with this method. Overall, RP-HPLC with fluorescence detection of SDB is a useful and powerful tool to measure biological sulfide levels.
Methods in Enzymology, 2015
Nitric oxide (NO) and hydrogen sulfide (H2S) are two major gaseous signaling molecules that regul... more Nitric oxide (NO) and hydrogen sulfide (H2S) are two major gaseous signaling molecules that regulate diverse physiological functions. Recent publications indicate the regulatory role of H2S on NO metabolism. In this chapter, we discuss the latest findings on H2S-NO interactions through formation of novel chemical derivatives and experimental approaches to study these adducts. This chapter also addresses potential H2S interference on various NO detection techniques, along with precautions for analyzing biological samples from various sources. This information will facilitate critical evaluation and clearer insight into H2S regulation of NO signaling and its influence on various physiological functions.
Nitric Oxide, 2012
ABSTRACT Introduction Hydrogen sulfide is a gaseous signaling molecule which is produced in vivo ... more ABSTRACT Introduction Hydrogen sulfide is a gaseous signaling molecule which is produced in vivo by three enzymes such as cystathionine γ-lyase (CSE), cystathionine β- synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (MST) from L-cysteine.CSE is the prime enzyme among others for sulfide production in vascular tissues of our body. Hydrogen sulfide is reported to have vasodilatory, anti–inflammatory, anti-oxidant, cytoprotective and pro-angiogenic effects. Sulfide production is decreased in diabetic condition. However, the molecular mechanisms of sulfide-mediated protection during chronic tissue ischemia in diabetic condition are completely unknown. Objective To determine molecular mechanisms involved in hydrogen sulfide mediated cytoprotection during chronic tissue ischemia in diabetic condition. Methods Hind limb ischemia was induced in 10 week old wild type, 42 week old Db/Db diabetic or 10–12 week old CSE knock out (CSEKO, n = 8, each group). PBS, 0.1, 0.5 and 1 mg/kg sodium sulfide (Na2S) was administered twice daily by retro-orbital injection. Hind limb perfusion was measured using a laser Doppler perfusion probe. SPY imaging was performed to determine the collateral formation in different time points. Capillary myofiber ratio was determined by NOVA Red staining with CD31 antibody. Mature vessel density and proliferation index were determined by the ratio of smooth muscle actin (SMA) to DAPI and Ki67 to DAPI positive areas respectively. TUNEL assay was measured to investigate the apoptosis. Nitric oxide (NO) was measured by NO analyzer (NOA). CPTIO (1 mg/kg/day) was injected intra-peritoneally to determine the effect of NO in sulfide induced ischemic angiogenesis. VEGF aptamer (50 mg/kg/day) was injected locally to the ischemic muscle to determine the role of VEGF in sulfide induced ischemic angiogenesis. Lastly, VEGF expression was determined by ELISA. Result Blood perfusion, blush rate by SPY imaging, angiogenic index, proliferation index and mature vessel density were significantly decreased in CSEKO mice compared WT mice indicating the role of sulfide on ischemic angiogeneis and arteriogenesis. Na2S dose dependently increases the angiogenesis index, proliferation index, mature vessel density and restores the blood flow in WT mice. Hydrogen sulfide also rescues the impaired blood flow in CSEKO mice by increasing angiogenic index, proliferation index and mature vessel density. Blood tissue perfusion, proliferation index, capillary to myofiber ratio and VEGF expression were all significantly increased and conversely, apoptosis was prevented in ischemic hind limbs of aged diabetic mice treated with Na2S compared to PBS control. There was no effect of sulfide on blood glucose, body weight and lipid profiles of diabetic mice.Total NO production was increased in sulfide treated group compared to PBS which was inhibited by CPTIO treatment. Lastly, VEGF164 aptamer blocked sulfide induced augmentation of blood flow and reduced the expression of VEGF164 in WT and diabetic mice hind limb ischemia indicating VEGF164 as the sulfide induced angiogenic stimulator. Conclusion Sodium sulfide therapy restores tissue perfusion of critical limb ischemia by increasing production of NO, increasing expression of VEGF and preventing apoptosis in diabetic mouse chronic hind limb ischemia which may be beneficial for the diabetic patient with peripheral vascular disease.
Nitric Oxide, 2013
Hydrogen sulfide (H 2 S) is the most recent endogenous gasotransmitter that has been reported to ... more Hydrogen sulfide (H 2 S) is the most recent endogenous gasotransmitter that has been reported to serve many physiological and pathological functions in different tissues. Studies over the past decade have revealed that H 2 S can be synthesized through numerous pathways and its bioavailability regulated through its conversion into different biochemical forms. H 2 S exerts its biological effects in various manners including redox regulation of protein and small molecular weight thiols, polysulfides, thiosulfate/ sulfite, iron-sulfur cluster proteins, and anti-oxidant properties that affect multiple cellular and molecular responses. However, precise measurement of H 2 S bioavailability and its associated biochemical and pathophysiological roles remains less well understood. In this review, we discuss recent understanding of H 2 S chemical biology, its relationship to tissue pathophysiological responses and possible therapeutic uses.
Nitric Oxide, 2013
ABSTRACT Although animal studies concerning cytokines or stem cell therapies have shown hope for ... more ABSTRACT Although animal studies concerning cytokines or stem cell therapies have shown hope for arteriogenesis, clinical results have been disappointing due to multi-factoral causes. Monocyte signaling is a dominant and important mediator of arteriogenesis activity and monocyte-signaling pathways can be severely impaired during various cardiovascular disorders. Hydrogen sulfide (H2S) is produced by cystathionine-γ lyase (CSE), and a potential gaseous molecule that has many positive cytoprotective effects including regulation of monocyte functions. However, a molecular mechanism of CSE/H2S regulation of arteriogenesis during ischemia is not established. Therefore, we hypothesized that CSE/H2S modulates arterial collateral formation in mouse hind limb ischemia via IL-16/bFGF dependent pathway. Unilateral permanent hind limb ischemia was induced in wild type (WT) and CSE(-/-) mice. Mice were then randomly assigned into four groups (8 mice, each group); WT PBS, WT DATS (a hydrogen sulfide donor, 200μg/kg, twice daily, IV until day 21), CSE(-) PBS, CSE(-/-) DATS. CSE activity and H2S levels in monocytes and tissues were determined in ischemic conditions and with inflammatory agents and studied both in vitro and in vivo. Tissue perfusion was determined using laser Doppler perfusion imaging system and the number and diameter of arterial collaterals measured using SPY angiography. Mature vessel density and monocyte recruitment was investigated by α-SMA/CD31/DAPI and MAC-2/DAPI positive staining. ELISA was used to measure IL-16 and bFGF levels. CSE activity and free H2S levels were increased during ischemia and TNF- α stimulation in cultured monocytes. CSE activity and H2S levels were also elevated in bone marrow derived and circulating monocytes, and tissues after ischemia induction in WT mice but not from CSE(-/-) mice. Blood perfusion, blush rate, number and diameter of collaterals, and mature vessel density were decreased in CSE(-/-) mice compared to WT mice that was rescued by DATS therapy. IL-16 levels were reduced in ischemic tissue of CSE(-/-) mice compared to WT mice. IL-16 levels were restored by DATS treatment in ischemic tissue of CSE(-) mice. Monocyte recruitment was significantly reduced in ischemic tissues of CSE(-/-) mice that were rescued by DATS treatment. Lastly bFGF levels were less in ischemic tissue of CSE(-/-) mice compared to WT mice and that were restored by DATS therapy. CSE/H2S regulates arteriogenesis via IL-16 mediated monocyte recruitment and up-regulation of bFGF levels in ischemic tissue of CSE(-/-) mice. These findings reveal a novel role of monocyte dependent CSE/H2S in regulating arteriogenesis activity.